every one that opens the womb: Heb. פֶּטֶר כָּל-רֶחֶם, which opened the womb first, [פֶּטֶר meaning to open] as “in The beginning of strife is like letting out (פּוֹטֵר) water” (Prov. 17:14); “ יַפְטִירוּ בְשָׂפָה, they will open their lips” (Ps. 22:8). — [from Mechilta, targumim]

Remember this day: This teaches us that we are to mention the Exodus from Egypt daily. — [from Mechilta]

זכור את היום הזה: למד שמזכירין יציאת מצרים בכל יום:

4Today you are going out, in the month of spring.

דהַיּ֖וֹם אַתֶּ֣ם יֹֽצְאִ֑ים בְּחֹ֖דֶשׁ הָֽאָבִֽיב:

in the month of spring: Now do we not know in what month they went out? [Early editions read: Now did they not know in what month they went out?] Rather, this is what he [Moses] said to them, “See the lovingkindness that He bestowed upon you, that He took you out in a month in which it is suitable to go out, when there is neither heat nor cold nor rain,” and so it says: “He takes the prisoners out at the most opportune time (בַּכּוֹשָׁרוֹת) ” (Ps. 68:7), in the month when it is best suited (כָּשֵׁר) to go out. — [from Mechilta]

5And it will come to pass that the Lord will bring you into the land of the Canaanites, the Hittites, the Amorites, the Hivvites, and the Jebusites, which He swore to your forefathers to give you a land flowing with milk and honey and you shall perform this service in this month.

into the land of the Canaanites, etc.: Although [Scripture] enumerated [here] only five nations, it means all seven [of the nations], for they are all included in the [term] Canaanites, [even though] there was one of the families of Canaan that had only the name Canaanite. — [from Mechilta; Tanchuma, Bo 12]

swore to your forefathers, etc.: Concerning Abraham, it says: “On that day, the Lord formed a covenant with Abram, [saying, ‘To your seed I have given this land’]” (Gen. 15:18); and concerning Isaac it says: “Sojourn in this land […for to you and to your seed I will give all these lands, and I will set up the oath that I swore to Abraham your father]” (Gen. 26:3); concerning Jacob it says: “the land upon which you are lying [to you I will give it and to your seed]” (Gen. 28:13). — [from Mechilta]

flowing with milk and honey: Milk flows from the goats’ [udders], and honey flows from the dates and the figs. — [from Kethuboth 111b]

זבת חלב ודבש: החלב זב מן העזים והדבש זב מן התמרים ומן התאנים:

this service: [that] of the Passover sacrifice (Mechilta, Pes. 96a, Mechilta d’Rabbi Shimon ben Yochai). Now was it not already stated above (12:25): “And it shall come to pass when you enter the land [that you should keep this service], etc.” Now why did [Scripture] repeat it? Because of the thing that was newly introduced in it. In the former chapter (12:26), it says: “And it will come to pass if your children say to you, ‘What is this service to you?’” [There,] Scripture refers to a wicked son, who excludes himself from the community [by saying “to you”], and here (verse 8), “And you shall tell your son,” refers to a son who does not know to ask. Scripture teaches you that you yourself should initiate the discourse for him (Mechilta 14) with words of the Aggadah, which draw his interest [lit., draw the heart]. — [from Mechilta 18:14]

Because of this: In order that I fulfill His commandments, such as these [commandments of] the Passover sacrifice, matzah, and bitter herbs. — [from Jonathan, Passover Haggadah]

בעבור זה: בעבור שאקיים מצותיו, כגון פסח מצה ומרור הללו:

the Lord did [this] for me: [Scripture] alluded to a reply to the wicked son, to say, “the Lord did [this] for me,” but not for you. Had you been there, you would not have been worthy of being redeemed. — [from Mechilta]

9And it shall be to you as a sign upon your hand and as a remembrance between your eyes, in order that the law of the Lord shall be in your mouth, for with a mighty hand the Lord took you out of Egypt.

And it shall be to you as a sign: The Exodus from Egypt shall be to you as a sign. — [from Jonathan]

והיה לך לאות: יציאת מצרים תהיה לך לאות:

upon your hand and as a remembrance between your eyes: This means that you shall write these passages [verses 1:10 and 11:16] and bind them on the head and on the arm.

על ידך ולזכרון בין עיניך: שתכתוב פרשיות הללו ותקשרם בראש ובזרוע:

upon your hand: On the left hand. Therefore, in the second section, (Verse 16) יָדְכָה is written with the full spelling, to explain thereby [that it means] the hand (יָד) that is weaker (כֵּהָה). — [from Men. 37b]

And it will come to pass when… will bring you: Some of our Sages learned from here that the firstborn that were born in the desert were not sanctified. The one who rules that they were sanctified explains this “entry” as saying: If you fulfill it [this commandment] in the desert, you will merit to fulfill it there [in the Holy Land]. — [from Bechoroth 4b]

That you shall give over: Heb. וְהַעִבַרְךְתָּ is only an expression of separation, and so [Scripture] states: “and you shall give over (וְהַעִבַרְךְתֶּם) his inheritance to his daughter” (Num. 27:8). — [from Mechilta]

and every miscarriage: Heb. שֶׁגֶר, an aborted fetus, which its mother ejected (ֹשֶֹשָגַּרְךְתּוֹ) and sent out before its time. The text teaches you that it is holy in regards to freeing the one that follows it. A fetus that is not aborted is also called שֶׁגֶר, like “the offspring (שְׁגַר) of your cattle” (Deut. 7:13), but this [verse] came only to teach [us] about the aborted fetus, because [Scripture] already stated: “whatever opens the womb.” If you say that the firstborn of an unclean animal is meant, [Scripture] came and explained elsewhere “of your cattle and of your flocks” (Deut. 15:19). In another way we can explain: “you shall give over to the Lord whatever opens the womb,” that the text speaks of the firstborn of man. — [from Mechilta]

firstborn donkey: But not the firstborn of other unclean animals (Mechilta). This is a biblical edict [decreed that the firstling donkey be redeemed] because the firstborn of the Egyptians were likened to donkeys. Moreover, because they [the donkeys] assisted the Israelites in their departure from Egypt, (for there was not a single Israelite who did not take donkeys from Egypt) laden with the silver and gold of the Egyptians. — [from Bech. 5b]

you shall redeem with a lamb: He must give the lamb to a kohen. The firstborn donkey is permitted to be used, and the lamb is the ordinary property [i.e., unconsecrated] of the kohen. — [from Bech. 9a, b] [I.e., the lamb has no sanctity and may be used by the kohen.]

תפדה בשה: נותן שה לכהן ופטר חמור מותר בהנאה והשה חולין ביד כהן:

you shall decapitate it: He decapitates it with a cleaver from behind and kills it (Bech. 13a). He caused the kohen to lose his money [by neglecting to give him the redemption lamb]. Therefore, he must lose his own money [by decapitating his donkey]. — [from Bech. 10b]

if your son asks you in the future: Heb. מָחָר מָחָר sometimes means “now” and מָחָר sometimes means “at a later time,” such as it does here and such as “In time to come מָחָר, your children might say to our children” (Josh. 22:24), which refers to the children of Gad and the children of Reuben. — [from Mechilta]

“What is this?”: This is [the question of] the simple child, [referred to in the Haggadah,] who does not know how to pose his question in depth, and asks a general question: “What is this?” Elsewhere it [Scripture] says: “What are the testimonies, the statutes, and the judgments, etc.?” (Deut. 6: 20). This is the question of the wise son. The Torah spoke regarding four sons: the wicked one (Exod. 12:26), the one who does not understand to ask (Exod. 13:8), the one who asks [a] general [question], and the one who asks in a wise manner. — [from Yerushalmi, Pes. 10:4]

15And it came to pass when Pharaoh was too stubborn to let us out, the Lord slew every firstborn in the land of Egypt, both the firstborn of man and the firstborn of beast. Therefore, I slaughter [for a sacrifice] all males that open the womb, and every firstborn of my sons I will redeem.

and for ornaments between your eyes: Heb. וּלְטוֹטָפֹת, tefillin. Since they are [composed of] four compartments, they are called טֹטָפֹת, ‎טט in Coptic meaning two, and פת in Afriki (Phrygian) meaning two (Men. 34b) [thus 2+2=4 boxes of tefillin]. Menachem (Machbereth Menachem p. 99), however, classified it [טוֹטָפֹת] with “Speak (הַטֵף) to the south” (Ezek. 21:2) and “Preach not (אַל-תּטִּיפוּ)” (Micah 2:6), an expression of speech, like “and as a remembrance” (Exod. 13:9), for whoever sees them [the tefillin] bound between the eyes will recall the miracle [of the Exodus] and speak about it.